feat(wallet): detect a corrupt target wallet on switch + offer -salvagewallet repair

When a switch fails, the failure modal now distinguishes a CORRUPT target wallet
from other failures and offers a one-click repair:
- The switch worker watermarks the node's captured console output before the
  start and, if the node dies in init, scans this start's output for a corruption
  signature ("Failed to rename … .bak" / "salvage failed" / "wallet.dat corrupt" /
  "Error loading wallet") → sets switch_wallet_corrupt_.
- The Failed modal then shows an accurate "this wallet appears corrupt" message
  (instead of the generic "Couldn't open that wallet") plus a "Try to repair
  (salvage)" button that retries the switch with the target node started under
  -salvagewallet (recovers readable keypairs; implies -rescan).
- EmbeddedDaemon::setSalvageOnNextStart (one-shot, precedence salvage > zap >
  rescan) + controller forwarder; switchToWallet gains a salvage arg.

Salvage operates only on the corrupt target (never the good wallet, no fund
movement). Adversarially verified: output isolation, one-shot lifecycle, state
handling, re-entrancy, no success-path regression.

i18n (EN + 8 languages) + 2 new CJK glyphs baked into the subset font.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

res/lang/ko.json

@@ -1294,6 +1294,8 @@
     "sweep_to": "쓸어담은 주소:",
     "sweep_toggle": "내 지갑으로 쓸어담기 (키 보관 안 함)",
     "sweep_tx": "거래:",
+    "switch_corrupt_body": "이 지갑이 손상된 것 같습니다. 노드가 열 수 없습니다. 백업에서 복원하거나 다시 만들거나 복구를 시도하세요.",
+    "switch_corrupt_repair": "복구 시도(salvage)",
     "switch_progress_background": "백그라운드에서 계속",
     "switch_progress_default_wallet": "기본 지갑",
     "switch_progress_elapsed": "경과",